1. Field of the Invention
The present invention relates to an image recording member used for an electrophotographic system, thermal transfer system and the like as well as a method for recycling such image recording member, and more particularly to an image recording member which can be recycled by repeating image formation with an image forming material on such image recording member and removal of the image forming material from the image recording member as well as a recycling method by utilizing such image recording member.
2. Description of the Related Art
Recently, there has been a growing interest in disposal of waste and reducing use of resources as environmental problems in global scope. Thus, disposal of image recording members such as paper, plastic films for overhead projector (OHP) and the like as well as reducing use of wood, petroleum and the like which are resources for the material have become important subjects. As one of countermeasures against wasteful use of resources, recycling of paper once used as waste paper has been developed, without disposal thereof. However, plastic films and the like for OHP use are scarcely recovered. Further, there are a variety of problems in recovery and recycling of such materials. More specifically, there are, for example, problems in leakage of confidential documents or confidential data on business, labor for classifying working of materials according to types of recording materials, practical cost required for recovery thereof, and places for collection and control of recovered materials, and problems of quality of recycled products, cost required for deinking inks or the like contained in the materials recovered with respect to reuse.
If such classified recovery, transportation, collection, and recycling of materials are not efficiently carried out, a large amount of energy is consumed, and resulting in increase in an amount of CO.sub.2 which is one of global environmental problems, so that there is a fear of accelerating further the warming phenomenon of the earth's atmosphere.
From the viewpoint of efficient deinking treatment, it is desired to release easily an image forming material such as, toner, and ink from an image recording member such as paper, OHP sheet and the like, while an image forming material must be firmly fixed onto an image recording member to maintain the image recorded. Namely, there is an antinomic relationship between fixability of an image and releasability thereof. Under these circumstances, a variety of manners for removing image forming material from image recording member have heretofore been proposed, but they involve a number of problems in themselves.
The related art will be described in more detail hereinafter.
Japanese Patent Application Laid-Open (JP-A) No. 4-362935 discloses a method for recycling an image recording member in which an image is formed by the use of a near infrared ray color-quenching type image recording member, as an image forming material, in which a color image is extinguishable by irradiating near infrared rays, and disused image is irradiated with near infrared rays thereby allowing to extinguish the color.
However, the invention of Japanese Patent Application Laid-Open (JP-A) No. 4-362935 involves such problems that since such near infrared ray color-quenching type recording material reacts also under natural light, there are problems such that image storability is a question, usable materials are limited and toner color is limited, resulting in poor color suitability, and change in characteristic of the image recording member since sue to remaining of toner binder in the image recording member after color-quenching, resulting in causing trouble of transfer ommission in case of reuse of the material (a phenomenon) that image portions which are not transferred are caused.
In light of drawbacks involved in the invention of Japanese Patent Application Laid-Open (JP-A) No. 4-362935. it is desirable to remove the image forming material itself from an image recording member, rather than quenching the color in the image fording material when the image forming material is reused.
As a manner for removing the image forming material from an image recording member, Japanese Patent Application Laid-Open (JP-A) No. 1-101577 discloses a method for removing toner from the image recording member by the use of an organic solvent. However, the invention of Japanese Patent Application Laid-Open (JP-A) No. 1-101577 involves a safety problem. because the method requires use of an organic solvent.
In addition to the above, Japanese Patent Application Laid-Open (JP-A) Nos. 7-104621 and 7-225540 disclose methods for recycling an image recording member in which the adhesive force between a toner and the image recording member is reduced by employing an aqueous solution containing a surfactant and the like, and then, the image recording member and an image releasing member are heated to transfer the toner to the image releasing member.
However, since these inventions utilize an aqueous surfactant solution being a liquid for reducing the adhesive force between the toner and the image supporting material, there arise such secondary problems that a large amount of energy is required for drying moistened paper, and that because the paper is moistened, the paper rends to wrinkle. Besides, there is also such problem that the contact characteristic between the toner and the image releasing member deteriorates due to the aqueous solution existing between them in the case that the image releasing member is allowed to be in contact with moistened paper, and as a result, the image cannot sufficiently be removed. Such tendency is observed particularly remarkable in the case where solid image, graphics or the like printed on the entire surface of the image recording member is released.
If the toner used is black toner, it is difficult to discriminate dot-like toner remained on the image recording member from printed decimal points and punctuation points after recycling the materials. Furthermore, there is such problem in case of color image that since the image density is high, a surfactant is hard to enter into an interface between the image and the paper, the releasability becomes much more insufficient so that accurate color reproduction cannot be attained after recycling the materials.
According to Japanese Patent Application Laid-Open (JP-A) No. 6-222604, a method for removing easily of an image forming material from the image recording member by reducing adhesion between the image forming material and the image recording member by the use of a resin layer which has been formed on the outermost layer of the image recording member and which swells with water has been proposed.
However, the invention of Japanese Patent Application Laid-Open (JP-A) No. 6-222604 involves such problem that since the image recording member itself becomes hydrophilic, the image forming ability varies with circumstances such as moisture and the like, so that the image quality cannot be maintained, in addition to the above described problems due to water.
Furthermore, according to Japanese Patent Application Laid-Open (JP-A) Nos. 1-297294 and 4-64472, a method for removing an image forming material in which the image forming material is fixed on paper which has been subjected to releasing treatment, and the paper is heated together with a releasing member in case of removing the image, whereby the image forming material is transferred to the releasing member has been proposed. However, the paper which has been subjected to releasing treatment exhibits low intermolecular force with respect co the image forming material which is made essentially from organic polymeric materials, so that the image forming material cannot sufficiently be fixed on such paper, even if heat or pressure is applied to them in the fixing step. In addition, the releasing material used for such releasing treatment has a low adhesiveness and low affinity with a substrate of the image recording member, and as a result, it is difficult to firmly bond the releasing material to a substrate of paper or plastic film for OHP use. Moreover, there are such problems that although increase in thickness of a releasable coating layer is required to exert its releasing effect, such increase in layer thickness results in remarkable decrease in fixing ability of an image forming material with respect to the image recording member, and on one hand, fixability changes significantly dependent upon fixing conditions in a printing device or types of image recording member. On the contrary, there is such problem that decrease in thickness of a releasable coating layer for maintaining fixability of the image forming material results in not only decrease in releasing performance, but also no repeating use of the materials, since the releasing material is released and sealed off together with the image forming material when the image forming material is released. Furthermore, since most of releasing materials exhibit insufficient transparency, there arises such problem that when such releasing material is utilized for an OHP film, the optical transmission thereof decreases, resulting in formation of a dark image or inferior image. Moreover, since such film is formed heretofore by dissolving a releasing material in an organic solvent, or by thermally fusing a releasing material, only a resin having a specified molecular weight or a specified chemical structure can be used for maintaining a good solubility in a solvent or good heat-resistance. Under these circumstances, for example, fluorine-base resins and the like must have been employed heretofore in spite of the fact that they are expensive, only a small number of them can dissolve in an organic solvent, and the workability of them is restricted.